For the million reasons why you might think he's not into you, there are at least a million more that could be the complete opposite. Hang in there, I know it's so tough to get out of your own head, but don't let it eat away at you.

Talk to Enthir at the college. He is a wood elf, on the second floor of the Hall of Elements. Talk to him, and there will be an option saying "I heard you're an elf who can get things" or whatever, he will ask if you have the coin, say yes and his shop will open. The dialogue may be different if you have progressed in the thieves guild. But, he normally has 1 or 2 daedra hearts in stock. His shop refreshes every 48 ingame hours i believe.